Talk:Gas engine

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Quote 1: "Generally the term gas engine refers to a heavy duty, slow revving industrial engine".

Quote 2: "Modern gas engines are of the high speed type—1500 rpm"

These two statements are contradictory. Biscuittin (talk) 12:27, 10 May 2009 (UTC)

Disputed content

Quote: "British engines mentioned above were of the slow-speed type—less than 1000 rpm—and used pilot diesel injection for ignition. Modern gas engines are of the high speed type—1500 rpm—and use spark ignition. British manufactures did not invest in developing the technology and were superseded by more forward-thinking suppliers."

I think the writer of the above section is confused between between dual-fuel engines (which can run on diesel alone, or diesel and gas, but not gas alone) and alternative fuel engines (which can run on either diesel or gas, but not both at the same time).

This is a matter of two different types of engine, not of British manufacturers being backward. Biscuittin (talk) 13:52, 10 May 2009 (UTC)

I have added a section on "Two fuels". Biscuittin (talk) 22:37, 10 May 2009 (UTC)

Energy balance

This section, too, is confused. A gas engine does not have an electrical efficiency. Electrical efficiency refers to an engine/generator package. Biscuittin (talk) 14:03, 10 May 2009 (UTC)

I have replaced "electrical efficiency" by "thermal efficiency". Biscuittin (talk) 14:18, 10 May 2009 (UTC)

Point taken but this section doesnt make sense anymore. The engine does have a mechanical efficiency which is used to drive the generator. The thermal efficiency is a different issue which relates to the successful recovery of waste heat.--Alex Marshall (talk) 10:10, 20 August 2009 (UTC)

Electrical efficiency has nothing to do with gas engines. This topic belong in a article about electrical generators driven by gas engines. As far as a gas engine is concerned the interesting efficiencies are thermal efficiency, energy conversion efficiency (the fuel energy to mechanical output energy), etc. --Sigmundg (talk) 02:27, 3 February 2012 (UTC)

A gas engine can not have an electrical efficiency. It has either a thermal or mechanical efficiency. Electrical efficiency belongs to generator subject. — Preceding unsigned comment added by PradoScience (talk • contribs) 06:51, 28 March 2012 (UTC)

Dual fuel engines

I've removed this as it's completely unrelated.

The key part of a "gas engine", as developed by Lenoir and as it is described here, is that it has a low compression ratio. This is OK for early gas fuels, but it can't run with fuels such as petrol, and especially not for compression-ignition diesel engines. These gas engines certainly don't then work as duel fuel engines. A duel fuel engine in that sense is a spark ignition petrol engine, with a minor addition to its carburation to work on gas too. It's not a gas engine that magically gains the compression needed for petrol or diesel. Andy Dingley (talk) 14:09, 26 May 2012 (UTC)

But, Dual fuel engine redirects here. Ought the hatnote be expanded? Jim.henderson (talk) 21:36, 18 February 2013 (UTC)

Dual fuel engine should never have redirected to gas engine in the first place, as the two techniques have never had any such connection. I've changed the redir to point to Multifuel, although that article could use improvement too. Andy Dingley (talk) 21:47, 18 February 2013 (UTC)

Spark ignited

About 6,810,000 results (0.34 seconds) on google

What's your point?, and before you try and make it would you please learn that a "gas engine" runs on gas, not gasoline, what its likely compression ratio is (and why this matters) and that it certainly isn't a synonym for a spark-ignition engine. Andy Dingley (talk) 22:57, 13 April 2013 (UTC)

I think you owe an apology. From your profile you seem to be computer geek not someone who knows about the spark ignited or diesel engine industry. Kindly see these examples: Caterpillar one of the large engine manufacturers in the world of gas engines routinely uses the phrase "Spark-ignited" to distinguish diesel engines and gas engines.: http://infohouse.p2ric.org/ref/31/30447.pdf "Application of CaterDillar Spark-Ignited Enrzines for Landfill Gas

BY

Curt E. Chadwick

Senior Application Consultant, Spark-Ignited Engines

Caterpillar Engine Division, Mossville, Illinois

Caterpillar has decades of experience operating spark-ignited engines on

medium Btu gas, a considerable number of which are performing successfully on

landfill gas recovery projects. A partial listing of our landfill gas engine

experience is given in Attachment A.

spark-ignited engines that can be operated successfully on landfill gas. Our

model 3516 low emission Engine used in single or multiple installations seems

to best fit the profile of economically feasible landfill power projects and

has been developed specifically for this purpose. The 3516 SITA is a 16

cylinder engine with a 170 x 190 mm bore and stroke, rated at 800 kW with 130"

aftercooler water. "

See also this Cat spec sheet which clearly uses the term Spark - Ignited

http://www.myfoleyinc.com/foleyinc/files/chp_Datasheet_460-820%20kW_G3516%201200%20RPM_2%20g%20NOx.pdf

Also see Jenbacher, and Austrian company:http://www.ecomagination.com/portfolio/jenbacher-j624-natural-gas-engine-for-combined-heat-and-power

"GE’s Jenbacher spark-ignited gas engines for combined heat and power applications are designed to achieve highest overall optimized efficiency, reducing fuel consumption compared to the separate production of heat and electricity." Deutz invented the Spark Engine:

1876: The spark ignition engine - Today in History - DW.DE

www.today-in-history.de/index.php?what=thmanu...

The company is now called Deutz AG, and Dietmar Voß is responsible for the ... The birthday of the spark ignition engine is deemed as being May 9, 1876. From the Deutz catalogue:

"914 Gas

General Product Features – Basic Engine Data

Air-cooled, four-stroke,, spark ignited, 4 and 6 cylinder in-line engines
Natural aspirated engines G914L04 / G914L06 are running with a “stoichiometric “

air-fuel ratio (λ : 1)

The turbo charged version TCG 914L06 is designed as “lean-burn” engine (λ : 1.4 - 1.5)
Integrated ignition and gas control system
High rate of parts commonality between Diesel and Gas engine types"

And the Japanes claim to make spark ignited engines:

ENGINE: Kubota adds 1.6-L spark-ignited engine to line

www.canadianminingjournal.com/.../engine-kubota...spark-ignited-engin...

Apr 17, 2012 – MARKHAM, Ontario – The new WG 1605 spark-ignited engine fromKubota Engine Division has the same reliability and performance as its ...

Gas engines are spark ignition engines. Not all spark ignition engines are gas engines. One term is not a synonym for another. Andy Dingley (talk) 10:38, 14 April 2013 (UTC)

I see that you've added this now for a 4th time. Still uncited. Why do you think that spark-ignition and gas engines are the same thing? Do you think that gas engines and gasoline engines are the same thing? Andy Dingley (talk) 15:29, 14 April 2013 (UTC)

Technical details

I think this section needs expanding. First, air/gas mixing. I doubt if modern engines use the venturi effect alone. I suspect there would be electronic control. Secondly, ignition. Is this identical to the spark ignition system of a petrol engine? Biscuittin (talk) 16:28, 9 August 2014 (UTC)

Dr. Drake 1843.

Dr. Alfred Drake, of Philadelphia, demonstrated a gas engine in 1843. Refs. in Google books, and Scientific American magazine. Also reported in English and Australian newspapers. It could use a variety of fuels including spirits of turpentine, and whiskey. 78.147.33.40 (talk) 23:18, 19 August 2016 (UTC)

Even earlier engines, and fuller history of internal combustion power :- http://albionalumni.org/chevrons/tech/pow/engIC.html78.144.86.134 (talk) 02:29, 20 August 2016 (UTC)

Compression ratio

What compression ratio is used in modern gas engines? Roberttherambler (talk) 11:43, 25 July 2017 (UTC)

High, for efficiency reasons. Same as a diesel engine can more closely approach the Carnot limit than a petrol engine, high CR pushes the efficiency limit higher.

Also it depends who made the gas engine. Older, simpler designs can often still be based on whatever the manufacturer's favourite engine design was at the time, and that used to mean small petrol car engines with low compression and a gas carb. There are plenty of Fiat SOHC engines, a 1970s design, still running as small generator / CHP plants in Europe. These needed very little redesign to make them into a gas engine that was practical for the standards of the day. If LPG is to be burned, then a mid-90s car engine, using a fuel system developed for Autogas, is another easy way. The LPG injectors are run in parallel with the original petrol injectors and a very, very simple monostable circuit is enough to match the LPG injector signals needed to the original petrol ECU. I believe 5 cylinder Volvo engines were a favourite for this. Andy Dingley (talk) 12:18, 25 July 2017 (UTC)

Can you be more specific? I assume a compression ratio of between 9:1 and 10:1 for petrol engines; between 14:1 and 16:1 for direct injection diesel engines; between 18:1 and 20:1 for indirect injection diesel engines. Where does a gas engine fit in this spectrum? Roberttherambler (talk) 12:41, 25 July 2017 (UTC)

"It depends". On the fuel, the size and the age.

Very old gas engines used lower CR than typical modern S-I petrol car engines. The first CHP natural gas car-conversion engines were made from the low-compression stock versions of petrol car engines. Smaller LPG engines ('90s) were made simply from car engines without changing the engine too much, other than adding a second fuel system. As both gases have a high octane number, CR isn't much of a limit though. Today, as fuel prices increase and efficiency becomes more of an issue, CRs rise.

Current technology, for either heavy vehicles (ie buses, I don't think there are many trucks doing this) with CNG, or for generator sets on piped LNG, they're based on diesel engine technology, using the same CRs and the dual-fuel diesel-based pilot fuel systems. This is because the makers are already in the diesel industry, the higher CR (up to about 18:1, and pretty much everything is direct injection these days) is efficient, and they're also possible to offer as conversion kits, with the gas supplied as a carburetted, but unignitable, fuel/air mixture and the injection pump timing shortened, to be just enough to ignite the main mix. Andy Dingley (talk) 13:12, 25 July 2017 (UTC)

I have added a section on ignition. Please check it for accuracy. Roberttherambler (talk) 18:18, 25 July 2017 (UTC)

Also, I cannot really add something here since Andy Dingley explained it well. The compression ration of an engine depends on many factors, basically, you would want to have your compression ratio as high as possible to have a better engine efficiency, on the other hand, a higher compression ratio means that the engine is prone to knocking, also, you have to keep in mind the exponential growth of compression required to increase the efficiency. This means that at a certain point an increase of compression wouldn't have a noticable effect on the engines efficiency. Sometimes the efficiency could be improved much more by reducing the compression ratio and adding a turbocharger. Cars that have naturally aspirated Otto engines capable of running on both gas and petrol ususally have a normal compression ratio around (10:1 – 11:1) Also, some experimental engines have a variable compression ratio. --Jojhnjoy (talk) 23:12, 25 July 2017 (UTC)

Flattery will still get you my vote for a TBAN at ANI. Andy Dingley (talk) 12:49, 26 July 2017 (UTC)

We probably need to look at splitting and reorganising these articles. Gas engine here grew as a historical article on 1900-ish stuff. "Dual fuel" also began as the military requirement in the 1960s to run on either diesel or petrol. Neither are the main topic of interest today. There's also a small market (a past trend? the future?) for dual fuel cars with petrol / LPG, mostly to avoid high petrol tax in some European countries.

The big issue right now - what I think Robert is looking for - isn't being covered well at all. These are the uses of piped natural gas to run generator sets or pumps, probably by a converted diesel engine using the pilot fuel CI injection system. We have almost nothing on these at present. Although they're called "duel fuel" by at least one maker selling their virtue for easy conversion of existing diesel designs, they're not a "dual fuel" in the sense of having "two fuels to choose from".

There are also the CNG buses, which may be technically different to this again, but are a topic of considerable current interest. Andy Dingley (talk) 12:49, 26 July 2017 (UTC)

I agree that we should split the articles. Possibly completely new lemmata would make sense for each engine or working principle. For instance, a lemma that explains the word Gas engine in general and links to further articles since the first Gas engine was the Lenoir engine; however, also Otto and Diesel engines as well as engines using not very common working principles could run on gas. Categorizing engines depending on their fuel type does not make so much sense in my opinion since basically an engine could be desinged to run on any fuel, Diesel engines for example could run on almost anything but Xylene and Benzene. Also, gas is just a state of aggregation, there are several different types of gas: LPG, CNG, LNG, wood gas, etc.

Afaik, the first engine that was designed to run on piped gas was the Lenoir engine back in the 19th century.

Since the NATO required military vehicles to run on petrol, usually all NATO vehicles have petrol engines, though not all of them are Otto engines; the Unimog 404 has a true Otto engine while the LG 315 has an OM 315 Diesel engine, also the Leopard I and MAN 630 have Diesel engines, surprisingly, the MAN's engine is not only capable of running on petrol but designed to run on it, the highest torque output is only achieved when it runs on petrol.

Dual- or Flex-fuel vehicles with Otto engines are usually either Gas/Petrol or Ethanol/Petrol capable. The German government decided to apply a fuel tax to Gas next year which will significantly increase the Gas prize. Interestingly though, usually a gas vehicle with an Otto engine cannot start on gas, it needs to start on petrol. The engine then switches to gas soon after it was started. Historical gas engines during WW II were usually designed for wood gas. I don't know too much about dual-fuel Diesel engines for generators, but for ships, especially gas tankers, these engines are a good alternative as gas tanker ships have huge gas tanks (obviously). They work with the pilot fuel CI injection system as Andy explained.

In my place some busses run on LPG and have Otto engines that are technically based on Diesel engines, though they have a spark plug ignition system. But it is not too uncommon to take an engine design and just put a new cylinder head on it to change the engine working principle. (At least it wasn't in the past, though the first car Diesel engine is not based on an Otto engine but on a truck engine. --Jojhnjoy (talk) 23:38, 26 July 2017 (UTC)

Speed control

How is speed controlled in a modern gas engine? If spark ignition is used, it could be controlled by throttling, as in a petrol engine. If compression ignition is used then I don't think throttling would work. With small throttle opening, there would not be enough compression to fire the charge. Roberttherambler (talk) 19:54, 25 July 2017 (UTC)

The fuel supply is controlled, although there's no throttle butterfly and no carburettor in the usual sense (a flow-sensitive constant-mixture supply). The pilot fuel supply is mostly constant, but I think this is used on its own for startup or off-load idling and is shut off to stop the engine. Andy Dingley (talk) 12:51, 26 July 2017 (UTC)

Am I right that the gas/air mixture is stoichiometric at all speeds other than idling? Roberttherambler (talk) 23:18, 26 July 2017 (UTC)

It's working like a diesel, so it will be much leaner than that, except near full power. The airflow is constant [sic], but the gas fuel supply is varied, according to load. As it's not an Otto cycle (rapid combustion and all the problems that entails) and there's a substantial pilot effect, you can get away with this level of lean-burn. Andy Dingley (talk) 10:40, 27 July 2017 (UTC)

If it's lean-burn, will there be the same pollution problem as a diesel, i.e. production of nitrogen dioxide? Roberttherambler (talk) 21:56, 27 July 2017 (UTC)

Of course, but I've no idea what level to and whether it's a problematic level. I don't work in the field these days and I'm way out of date on these. But NO_x reduction isn't rocket science these days - we have catalysts and urea fluids.

The only time I worked on diesel exhausts was in the early '90s and we were focussing on visible smoke and particulates - largely the IR visibility of exhaust plumes, as this was military - warm soot is a lovely target! Back when "lean burn" was seen as a good thing. But since then we have vehicles like the recent VW cars and all that controversy. Where, even running in maximum-lying-and-cheating-mode, they're still some of the cleanest diesel engines ever built. This is a problem, but it's a problem we have fixes for.

As ever, the problem with road diesels is their maintenance after a few years. One clapped out old van has the emissions of a thousand new ones. Andy Dingley (talk) 22:22, 27 July 2017 (UTC)

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